As one of basic components of a railway vehicle, the coupling buffer has the advantages of rapidly connecting and disconnecting railway vehicles, transmitting vehicle tractive force, improving vehicle safety and comfortability.
The coupling buffer essentially comprises a coupling device, a squashing device, a buffer device, a front suspension device and an overload protection device. The coupling device has the function of connecting and disconnecting railway vehicles; the squashing device has the function of protecting vehicle body and passenger safety in emergency; as a coupling buffer, the buffer device has the function of improving the longitudinal impulse performance and vehicle safety and comfortability; fixing a coupler onto the vehicle body by means of the mounting seat, the front suspension device guarantees that the coupling buffer can flexibly rotate within certain limits in the horizontal plane and vertical plane, and has the functions of self-support in the vertical plane and automatic centering within certain limits in the horizontal plane; when railway vehicles suffer from great longitudinal impact, the overload protection device facilitates the coupling buffer to separate from vehicles, and further facilitates other energy absorbing devices on vehicles to come into play. As an important energy absorbing device in the coupling buffer, the buffer mainly takes part in longitudinal energy absorption in the normal running process of railway vehicles. Many existing buffers realize the function of energy absorption by means of compressing internal elastic components, while a buffer itself is connected to the mounting seat by means of a rotation axle so as to realize the function of rotation of the coupling buffer. The mounting seat is connected to vehicle body by means of an erection bolt or the overload protection device so as to transmit longitudinal load.
At present, commonly the overload protection device is arranged on the outside of the coupling buffer, directly connecting the coupling buffer with vehicle body, and facilitates the coupling buffer to separate from the vehicle body once it comes into play. The existing coupling buffer of railway vehicles essentially comprises a front suspension system and a buffer system. There are three methods for realization of the overload protection function of the buffer: the first method is to break the connection between the mounting seat and the vehicle body, the second method is to equip the buffer shell with a shear pin so as to realize retreat of a buffer core in a coupler body by destroying the shear pin, and the third method is to break the connection between the mounting seat and the coupling buffer. At present the first method is widely used because of easy realization, but requires for a small-sized mounting seat and buffer or enough space left under the vehicle body so that the whole coupling buffer separates from the vehicle body and retreats. However, restricted by the existing structure and strength, the opening size of the chassis of the vehicle body is difficult to enlarge. However, a high-performance buffer device requires for larger space left for retreating, which greatly restricts the application scope of the first method for realization of overload protection function. The second method has the disadvantage of uneven stress of the shear pin, unavailable for good realization of overload protection; besides, the space for retreat of the coupling buffer is influenced by the total length of the coupling buffer, often unable to provide enough space for safely retreating.